Expansible back cap



FIG. 1 is a front perspective view of my expansible back cap showing how the same is worn by a person;

FIG. 2 is a right side elevational view of my expansible back cap with the left elevational view being a mirror image thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a front view thereof; and,

FIG. 6 is a rear view thereof.

The portions shown in broken lines are for illustrative purposes only and form no part of the claimed design. 

I claim the ornamental design for an expansible back cap, as shown and described. 